2 THE FLOWERING PLANT. 
resemblances which connect plants into groups are not the result 
of mere chance, but express actual relationship, what, in animals, 
would be called ‘blood ’’-relationship. The different groups of 
plants do not form a “ linear series,” 2.¢., they cannot, as regards 
affinity, be placed in a line, the most complex members of one 
group coming just below the least complex of the next group, and 
so on; but they naturally fall into a tree-like arrangement. This 
is now believed to represent, in a general sort of way, a genea- 
logical tree. The second great use of Systematic Botany is, there- 
fore, to help in the construction of plant-genealogies. Apart from 
the great theoretical interest attaching to this kind of work, there 
is a very practical application affecting medicine and many manu- 
factures. Broadly speaking, closely related plants have similar 
properties, and a classification which represents affinities with fair 
accuracy will be of the greatest service in the search for new 
drugs, dyes, fibres, &c., &c. The uses, if any, of a newly-discovered 
plant can also be judged of with some accuracy even without 
experiment. The branch Economic Botany, which deals with the 
question, ‘‘Of what use to man?” is therefore an appendix to 
Systematic Botany. The present volume, however, has little or 
nothing to do with this branch, nor is it concerned with Geo- 
graphical and Fossil Botany, which endeavour to answer the 
questions, ‘‘ Where found?” and ‘When found?” that is to 
say, try to elucidate problems regarding distribution in space 
and time. 
Differences between Plants and Animals.—It might at first 
be thought that plants, with which Botany deals, could easily be 
distinguished from animals, which form the subject-matter of the 
sister science, Zoology. No one is in danger of confounding a 
cow with a cabbage, and, as a matter of fact, ordimary plants are 
marked off with sufficient distinctness. But when we come to 
lower forms, often of minute size, it is frequently difficult to say 
for certain whether a given form be plant oranimal. The recog- 
nition of this fact has emphasized the close connection between 
the two divisions of the organic world, and called into existence 
the science of Biology, which deals with life generally, and in- 
cludes both Botany and Zoology. 
The largest subdivisions of the vegetable kingdom are those of 
Flowerless Plants (Cryptogams) and Flowering Plants (Phanero- 
gams), without and with conspicuous flowers respectively. What 
flowers exactly are will be seen in the sequel. We shall here 
deal, from an elementary point of view, with Flowering Plants 
only. These differ from animals in several important par- 
ticulars :— 
(1.) A typical member of the group is dependent upon gaseous 
